This invention is directed to test strips for determination of characteristics of samples, unitized housings, and kits incorporating the test strips, and methods of determining the characteristics of samples using the test strips.
Among the many analytical systems used for detection and/or determination of analytes, particularly analytes of biological interest, are chromatographic assay systems. Among the analytes frequently assayed with such systems are:
(1) hormones, such as human chorionic gonadotropin (hCG), frequently assayed as a marker of human pregnancy; PA1 (2) antigens, particularly antigens specific to bacterial, viral, and protozoan pathogens, such as Streptococcus, hepatitis virus, and Giardia; PA1 (3) antibodies, particularly antibodies induced as a result of infection with pathogens, such as antibody to the bacterium Helicobacter pylori and to human immunodeficiency virus (HIV); PA1 (4) other proteins, such as hemoglobin, frequently assayed in determinations of fecal occult blood, an early indicator of gastrointestinal disorders such as colon cancer; PA1 (5) enzymes, such as aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, and glutamate dehydrogenase, frequently assayed as indicators of physiological function and tissue damage; PA1 (6) drugs, both therapeutic drugs, such as antibiotics, tranquilizers and anticonvulsants, and illegal drugs of abuse, such as cocaine, heroin, and marijuana; and PA1 (7) vitamins. PA1 (1) a first opposable component including a sample preparation means adapted to receive a sample to be assayed; and PA1 (2) a second opposable component including a chromatographic medium. PA1 (1) applying the sample to the sample preparation means of the chromatographic assay device; PA1 (2) applying a detection reagent to the sample preparation means, the detection reagent comprising at least one component capable of binding specifically to analyte present in the sample; PA1 (3) bringing the first and second opposable components into opposition so that the sample preparation means applies the sample and the detection reagent to the chromatographic medium; PA1 (4) allowing the sample and the detection reagent to move through at least a portion of the chromatographic medium so that the detection reagent gives a detectable indication of the presence and/or quantity of the analyte; and PA1 (5) observing and/or measuring the detection reagent in at least a portion of the chromatographic medium in order to detect and/or determine the analyte. PA1 (1) applying the sample as an aqueous liquid to the sample preparation means of the chromatographic assay device, thereby resolubilizing the specific binding partner for the analyte with the detectable label so that the labelled specific binding partner can bind specifically to analyte present in the sample; PA1 (2) bringing the first and second opposable components into opposition so that the sample preparation means applies the sample and the labelled specific binding partner to the chromatographic medium; PA1 (3) allowing the sample and the labelled specific binding partner to move through at least a portion of the chromatographic medium so that the labelled specific binding partner gives a detectable indication of the presence and/or quantity of the analyte; and PA1 (4) observing and/or measuring the labelled specific binding partner in at least a portion of the chromatographic medium in order to detect and/or determine the analyte. PA1 (1) a first opposable component including: PA1 (2) a second opposable component including: PA1 (1) a first opposable component including: PA1 (2) a second opposable component including a fluid-conducting connecting member. PA1 (1) a first opposable component including: PA1 (2) a second opposable component including: PA1 (1) A first opposable component including; PA1 (2) a second opposable component including: PA1 (3) a cover hingedly attached to the first opposable component so that it can be folded over the first and second opposable components when they are opposed. PA1 (1) a first opposable component including: PA1 (2) a second opposable component hingedly attached to the first opposable component including: PA1 (1) a third opposable component hingedly attached to the first opposable component including: PA1 (1) a first opposable component including: PA1 (2) a second opposable component including an application means containing a specific binding partner for the analyte labelled with a detectable label in a form that can be resolubilized by the addition of an aqueous liquid to the application means. PA1 (1) a first opposable component including: PA1 (3) an absorbing means in operable contact with the second end of the chromatographic medium; and PA1 (2) a second opposable component including: PA1 (1) a first opposable component including: PA1 (2) a second opposable component comprising: PA1 (1) a first opposable component including: PA1 (b) a second opposable component including a sample application pad. PA1 (1) a first opposable component including: PA1 (2) a second opposable component including a sample application pad. PA1 (1) a first opposable component including a plurality of sample preparation means, each adapted to receive a sample of the assay; and PA1 (2) a second opposable component including as many chromatographic media as are present sample preparation means on the first opposable component. PA1 (1) a first opposable component adapted to receive the test card; PA1 (2) a second opposable component including a reagent pad that is placed in contact with the specimens when the test card is placed in the first opposable component and the first and second opposable components are brought into opposition; and PA1 (3) a third opposable component including a plurality of chromatographic media, one for each sample to be tested. PA1 (1) a first opposable component including a plurality of laterally separated reagent pads; and PA1 (2) a second opposable component adapted to receive a test card containing a plurality of dried specimens, the second opposable component including:
Such chromatographic systems are frequently used by physicians and medical technicians for rapid in-office diagnosis and therapeutic monitoring of a variety of conditions and disorders. They are also increasingly used by patients themselves for at-home monitoring of such conditions and disorders.
Among the most important of such systems are the "thin layer" systems in which a solvent moves across a thin, flat absorbent medium.
Among the most important of tests that can be performed with such thin layer systems are immunoassays, which depend on the specific interaction between an antigen or hapten and a corresponding antibody. The use of immunoassays as a means of testing for the presence and/or amount of clinically important molecules has been known for some time. As early as 1956, J. M. Singer reported the use of an immune-based latex agglutination test for detecting a factor associated with rheumatoid arthritis (Singer et al., Am. J. Med. 22:888-892 (1956)).
Among the chromatographic techniques used in conjunction with immunoassays is a procedure known as immunochromatography. In general, this technique uses a disclosing reagent or particle that has been linked to an antibody to the molecule to be assayed, forming a conjugate. This conjugate is then mixed with a specimen and, if the molecule to be assayed is present in the specimen, the disclosing reagent-linked antibodies bind to the molecule to be assayed, thereby giving an indication that the molecule to be assayed is present. The disclosing reagent or particle can be identifiable by color, magnetic properties, radioactivity, specific reactivity with another molecule, or another physical or chemical property. The specific reactions that are employed vary with the nature of the molecule being assayed and the sample to be tested.
Immunochromatographic assays fall into two principal categories: "sandwich" and "competitive," according to the nature of the antigen-antibody complex to be detected and the sequence of reactions required to produce that complex. In general, the sandwich immunochromatographic procedures call for mixing the sample that may contain the analyte to be assayed with antibodies to the analyte. These antibodies are mobile and typically are linked to a label or a disclosing reagent, such as dyed latex, a colloidal metal sol, or a radioisotope. This mixture is then applied to a chromatographic medium containing a band or zone. This band or zone contains immobilized antibodies to the analyte of interest. The chromatographic medium often is in the form of a strip resembling a dipstick. When the complex of the molecule to be assayed and the labelled antibody reaches the zone of the immobilized antibodies on the chromatographic medium, binding occurs and the bound labelled antibodies are localized at the zone. This indicates the presence of the molecule to be assayed. This technique can be used to obtain quantitative or semi-quantitative results.
Examples of sandwich immunoassays performed on test strips are described by U.S. Pat. No. 4,168,146 to Grubb et al. and U.S. Pat. No. 4,366,241 to Tom et al. both of which are incorporated herein by this reference.
In addition to immunochromatographic assays, it is also known to use enzyme-based chromatographic assays. These techniques are roughly analogous to immunochromatographic assays, but use an enzymatically catalyzed reaction instead of an antigen-antibody reaction. The enzymatically catalyzed reaction frequently generates a detectable product. Other analogous chromatographic assays are known.
Although useful, currently available chromatographic techniques using test strips have a number of drawbacks. Many samples, such as fecal samples, contain particulate matter that can clog the pores of the chromatographic medium, greatly hindering the immunochromatographic process. Other samples, such as blood, contain cells and colored components that make it difficult to read the test. Even if the sample does not create interference, it is frequently difficult with existing chromatographic test devices to apply the sample to the chromatographic medium so that the sample front moves uniformly through the chromatographic medium to insure that the sample reaches the area where binding is to occur in a uniform, straight-line manner.
Sample preparation and waste generation are responsible for other problems with currently available devices and techniques for immunochromatography. The increased prevalence of diseases spread by infected blood and blood fractions, such as AIDS and hepatitis, has exacerbated these problems. It is rarely possible to apply a sample (such as feces) or a sampling device (such as a throat swab) directly to the chromatographic medium. Several extraction and pretreatment reactions are usually required before the sample can be applied to the chromatographic medium. These reactions are typically carried out by the physician or technician performing the test in several small vessels, such as test tubes, or microfuge tubes, requiring the use of transfer devices, such as pipettes. Each of these devices is then contaminated and must be disposed of using special precautions so that workers or people who may inadvertently come into contact with the waste do not become contaminated.
Still another limitation on chromatographic devices currently available for use by the clinician or technician is their inability to perform two-directional or two-dimensional chromatography. These techniques have long been known to be powerful analytical tools, but their complexity relative to simple unidirectional chromatography has made it difficult to apply them to test strip devices in the physician's office or a clinical laboratory.
Accordingly, there is a need for an improved chromatographic device for the performance of immunochromatographic assays or other analogous assays. Such a device should be capable of receiving a possibly contaminated sample or a sample preparation device directly so as to eliminate the need for extraction vessels and transfer devices. Such a device, preferably in the form of a test strip, should also be capable of performing immunochromatographic assays on colored samples or samples containing particulates without interference and should-be able to deliver the sample to the chromatographic medium uniformly and evenly to improve accuracy and precision of the tests. Additionally, such an improved test strip should be capable of performing two-directional or two-dimensional chromatography when used in clinical laboratories or physicians' offices.